The present invention relates to a composition for marking a message on a the surface of a porous substrate, such as concrete, and a method of using a penetrating protective sealer for marking a message onto the surface of a porous substrate. The message of the instant invention is only visible while the surface is wet.
Various protective sealers have been developed to protect concrete, masonry, stone and other porous substrates from the deleterious effects of the environment such as water, chlorides and airborne pollutants. These protective sealers can be categorized into two types: (1) surface-coating sealers; and (2) penetrating sealers. Both types of protective sealers originate as liquids that can be applied using either rollers, brushes, low pressure sprayers, or cartridge-type applicators.
Surface-coating sealers, such as paints, varnishes, and most stains, generally remain on the surface of the treated substrate to act as a shield to protect the substrate from the deleterious substances. These surface coatings form a continuous film on the surface of the substrate that remains visible under both wet and dry conditions. For example, a non-pigmented surface-coating sealer will often shine when applied to a concrete surface. If only a portion of the concrete surface is treated with the surface-coating sealer, only the treated portion will shine. Additionally, the treated portion of the surface will have a slightly different texture and contour than the untreated portion of the surface due to the continuous film.
As an alternative to surface coatings, penetrating sealers are specifically designed to form discontinuous films and effectively penetrate the treated substrate. Because penetrating sealers form discontinuous films on a surface, both treated and untreated portions of the surface will have virtually identical textures and contours. As a result, a non-pigmented penetrating sealer will not be visible under dry surface conditions.
A principle object of the present invention is to provide a method for forming a message on a porous surface, such as concrete, that is only visible under wet conditions. This object is accomplished by forming a desired message onto the surface with a non-pigmented penetrating sealer. An indicator dye (also called a fugitive dye) may be added to the sealer to aid application. Upon complete curing of the sealer, the indicator dye will no longer be visible on the surface. The penetrating sealer originates in a liquid form that can be applied to the surface using standard painting equipment such as rollers, brushes, low pressure sprayers, and cartridge-type applicators, or any other suitable application tool. The desired message is painted onto the surface with the liquid penetrating sealer; the remainder of the given surface is left untreated. Once the penetrating sealer has fully reacted with the treated substrate, the sealer will form a discontinuous film over the treated portion of the surface that is virtually invisible under dry conditions. Under wet conditions, the treated portion of the surface will repel water while the untreated portion will absorb water. This will result in a variance in color between the treated and untreated portions of the surface. For example, where the surface is concrete, the untreated portion will be darker in color because it absorbs water, while the treated portion will be lighter in color because it remains dry. Thus, when a message has been painted onto the surface with the sealer, it will become visible under wet conditions.
In general, penetrating sealers are designed as protective sealers, which are to be applied to the entire exposed surface of a treated substrate. For example, water base siloxane penetrating sealers have a rather low viscosity to allow for easy spreading over the entire surface of a concrete sidewalk or driveway, and to allow deep penetration into the pores of the concrete. Because the object of the instant invention is to provide a message, the inventive method, which treats only a portion of the surface, contradicts the intended protective use of penetrating sealers. Thus, the low viscosity of current protective penetrating sealers results in bleeding around the outer edges of the treated portion of the surface, which in turn results in jagged edges for the message. It is desirable to have crisp, clean, neat edges in a message to increase legibility of the message. Therefore, it is an object of the instant invention to provide a composition that does not result in a bleeding effect around the edges of a desired message. This object is achieved through the addition of a thickening agent (also referred to as gums) to the sealer to add viscosity and prevent bleeding. In the example of a siloxane sealer, hydroxy ethyl celluose can be used as a thickening agent.
When a determined message is intended to cover a rather large area, the use of the thickened composition may be less desirable. In such a situation, the thickened composition can be used to outline the message, and the standard, non-thickened, penetrating sealer can be used to fill in the outlined message. This method will allow increased application efficiency, while at the same time maintain a neat edge for the message.
The foregoing and other objects are intended to be illustrative of the invention and are not meant in a limiting sense. Many possible embodiments of the invention may be made and will be readily evident upon a study of the following specification and accompanying drawings comprising a part thereof. Various features and subcombinations of invention may be employed without reference to other features and subcombinations. Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings, wherein is set forth by way of illustration and example, an embodiment of this invention.